NIST TRACEABLE CALIBRATION SOURCES:

Radioactive Calibration Standards

NTS provides instrument calibration standards for Gamma spectroscopic measurements for wide energy range calibrations of high purity germanium detectors (HPGe) or sodium- iodide detectors; Gas flow proportional counter for gross alpha-beta and beta emitting radionuclide measurements; Alpha spectrometric systems for measurements of alpha emitting radionuclide and Liquid Scintillation counting systems for H-3, C-14 and other beta emitting radionuclide.

Each standard is prepared gravimetrically with a NIST traceable calibrated balance. After preparation, the standard is counted with a calibrated counting system. The counting efficiencies are compared to the counting efficiency of at least one independent standard and agreement must be within NTS stated uncertainty.

The calibration standards are prepared to meet NTS quality-assurance and quality-control requirements. NTS supplied calibration standards are either prepared directly from NIST traceable standards and/or their activities characterized by using gamma spectroscopy systems or other counting instruments which are calibrated using NIST traceable standards.

The NTS standard operating procedures to provide NIST traceability are controlled under NTS quality assurance and quality control program. The NTS quality assurance program is based on and complies with ANSI NQA-1 requirements. The NTS QA and QC program also satisfies the requirements of the United States ' Nuclear Regulatory Commission's Regulatory Guide 4.15, Revision 1, 1979, and ANSI N42.22-1995 American National Standard - Traceability of Radioactive Sources to the National Institute of Standards and Technology (NIST) and Associated Instrument Quality Control.

Mixed Radionuclide Standards for Gamma Spectroscopy

NTS provides instrument calibration standards for Gamma spectroscopic measurements for wide energy range calibrations of high purity germanium detectors (HPGe) or sodium- iodide detectors;

Each standard is prepared gravimetrically with a NIST traceable calibrated balance. After preparation, the standard is counted with a gamma spectrometric system calibrated with NIST traceable standard. The counting efficiencies are compared to the counting efficiency of at least one independent NIST traceable standard and agreement must be within NTS stated uncertainty.

Single-Radionuclide Gamma Spectroscopy Standards

NTS can also provide single-radionuclide standards in custom specified geometry utilizing a wide variety of radionuclide. Contact us with your specifications of radionuclide, activity and geometry.

Matrices

• Water-equivalent solid standards prepared in various different geometries.
• Air Filter standards uniformly deposited per customers’ specifications and sealed in customer supplied geometry configurations.
• Charcoal and silver zeolite cartridge standards are prepared in cartridges loaded to customer specifications.
• Soil or sand standards in customer supplied counting containers with matrix density ranging from 1.5 g/cc to 1.7 g/cc.
• Vegetation or simulated vegetation standards in customer supplied counting containers with an approximate density of 0.6 g/cc.
• Simulated gas standards in customer supplied gas counting containers.
• Point sources in various geometries to customer specifications.

Call us for your geometry needs. Each standard is prepared gravimetrically with a NIST traceable calibrated balance. After preparation, each standard is counted with a calibrated detector system.

Airborne Radio-Iodine Determination

NTS supplies mixed and single radionuclide gamma-ray standards for airborne radio-iodine determinations. The calibrated radionuclide solution is gravimetrically dispensed and evaporated on activated charcoal or silver zeolite then is sealed in the customer's canister or cartridge. The activity can be deposited on the first 3 to 5 mm of the charcoal or zeolite material to simulate the distribution found in actual samples (face-loaded) or homogenously loaded throughout the cartridge per customer required applications.

Charcoal or silver zeolite canister or cartridge standards can be prepared using NIST traceable mixed gamma-ray standard or using single radionuclides such as ¹²⁵I or ¹³¹I.  In applications where gamma-ray coincidence summing is not a problem, ¹³³Ba can be used.

Gas Standards

The NTS simulated-gas standards provide calibration for gamma-ray spectrometers over a wide energy range. The standards are prepared using NIST traceable mixed gamma-ray standard mixtures deposited on a low-density polystyrene matrix in customer’s actual counting containers. The matrix has a density of 0.015 to 0.020 g/cc.

All simulated-gas standards are prepared gravimetrically from NIST traceable solutions and QC tested against actual gas standards in the same geometry.

Airborne Particulate and Wipe-Test Determinations

NTS supplies custom-geometry filter-paper standards that provide accurate calibrations for air particulate and contamination (wipe test) measurements. The alpha and beta filter-paper standards are Mylar™ covered and calibrated in total activity contained in the standard. The Mylar™ covering gives realistic attenuation characteristics and the custom mounting using the customer's filter and planchet gives realistic backscattering characteristics. The Mylar™ covering can be 0.5, 0.85 or 1.7 mg/cm2 depending on the application. Other coverings are available upon request.

The filter standards are prepared gravimetrically from calibrated solutions. A wide variety of alpha, beta or gamma-ray emitting radionuclide can be used. The covering and filter composite is then mounted in the customers' planchet or specified backing for counting. The calibration of the standard comes from the gravimetric preparation and is given in total activity contained in the standard. The filter standards can be prepared with a wide variety of active areas to accurately reproduce the actual counting geometry: circular, semi-circular, a quarter circle to simulate a folded filter, square, rectangular and many others. For special applications the activity can be made to vary across the active area.

Planchets (Simulated Evaporated Liquid)

Planchet standards simulating an evaporated liquid are prepared for use in gross alpha and gross beta determinations. As with the filter standards, the standard is prepared gravimetrically on Mylar™. The Mylar™ is mounted directly in the customer's planchet without a filter or backing. The backscatter and attenuation characteristics simulate an evaporated liquid in a planchet with a solid residue of approximately 0.5 or 0.85 mg/cm².

⁹⁹Tc calibrated for only beta emission rate is available, and can be prepared on 24.1-mm or 47.1-mm steel disks with various active areas.

Electrodeposited Standards

NTS supplies custom geometry electrodeposited standards for alpha spectrometry. The standards can be prepared on 19.2 mm, 24.1 mm or 47.1 mm stainless steel disks with various active areas. The following mixtures of radionuclides are available:

• Natural Uranium, ²³⁹Pu and ²⁴¹Am
• ²³⁰Th, ²³⁹Pu and ²⁴⁴Cm
• ²³⁰Th, ²³⁹Pu, ²⁴⁴Cm and ²⁴¹Am

Single radionuclide standards are prepared using any of the radionuclides in the mixtures as well as 238Pu and isotopes of uranium.  All standards are calibrated in total alpha emission rate measured by gas-flow or scintillation counting.

Liquid Scintillation Counting Standards

Quenched

Custom quench standard sets (typically 5-10 vials) for liquid scintillation counting can be prepared using the customer's LS counting fluid (cocktail). Standards are prepared gravimetrically and flame sealed in glass LS vials. Radionuclide available include, but are not limited to the following:

• ³H
• ¹⁴C
• ³⁶Cl
• ⁵⁵Fe
• ⁶³Ni
• ⁹⁹Tc
• ⁸⁹Sr
• ⁹⁰Sr

After preparation, the quenched sets are counted on one of NTS's calibrated liquid scintillation counting systems. Contact us with your specific requirements. Customers can supply their specific type of liquid scintillation vials.

Unquenched

A set contains ³H, ¹⁴C, and a background sample. Activities are 5 kBq (300,000 dpm) for ³H and 2.16 kBq (130,000 dpm) for ¹⁴C.

Alpha/Beta

A set contains ²⁴¹Am, ³⁶Cl and a background sample. Typical activities are 1.6 kBq (100,000 dpm) for each isotope. Other radionuclides and activities are available upon request.

Call or email for quotes, questions or special requests.